請問IPT文法題 - 英檢

各位大大，不好意思~

因為在做文法題，因為遇到問題，不知道是否適合來這裡發問？

題目：

First designated in 1970, Earth Day has become an annual international

event_______ concerns about environmental issues such as pollution.

(a)dedicated to raising

(b)dedicated raising

(c)dedicateds to raise

(d)that dedicates to raising

答案是(a)，但我是選(d)

能不能請問為何是(a)不是(d)呢？

謝謝各位大大了~~

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